Preparation of long chain organic isocyanates



Patented May 11, 1943 UNITED STATES PATENT v OFFICE PREPARATION OF LONG CHAIN ORGANIC ISOCYANATES William Edward Hanford, Wilmington, Del, as-

signor to E. I. du Pont de Nemours & Company, Wilmington, Del., a corporation of Delaware No Drawing. Application March 1938,

Serial No. 196,087

1 1. Claim.

through 250 parts of toluene at C. for 20 minutes, when a solution of 56 parts of n-dodecylamine in 45 parts of toluene was added rapidly with stirring. The mixture was heated to boiling and phosgene was passed in until hydrogen chloride was no longer given off. After removatoms and a: is the valence of R, or a hydrohalide of such amine, is reacted with phosgene in the presence of a diluent which is a solvent for the reactants and chemically inert toward reactants and product, at a temperature above about 75 C. The corresponding isocyanates R(NCO) are obtained directly in good yields.

Gattermann and Schmidt, Ann. 244, (1888), reacted methylamine with phosgene but obtained methylcarbamyl chloride which required treatment with alkali for conversion to the isocyanate. Jeffreys, Am. Chem. J. 22, 27 (1899) heated pentadecylamine hydrochloride with phosgene under pressure and obtained pehtadecylcarbamyl chloride. I have found that, if the reaction between phosgene and a high molecular weight aliphatic amine is conducted in the presence of a solvent of the above type, the desired isocyanate can be obtained directly and the intermediate special treatments to decompose the carbamyl' chloride are avoided.

The more detailed practice of the invention is illustrated by the following examples, wherein parts given are by weight. There are of course many forms of the invention other than these specific embodiments.

Example I yield of n-dodecyl isocyanate was obtained, dis- 4 tilling at 145 C. at 16 mm.

Example II n-Dodecyl isocyanata-Phosgene was bubbled mg the toluene an yield of n-dodecyl isocyanate was obtained by vacuum distillation of the residue.

Example III n-Octadecyl isocyanate.-To a solution of 80 parts of phosgene in 450 parts of toluene was added with stirring 135 parts of n-octadecylamine in 850 parts of toluene. The mixture was heated to boiling and phosgene was passed in until hydrogen chloride was no longer given off. The toluene was removed and an 80% yield of n-octadecyl isooyanate was obtained boiling at 172-173 C. at 5 mm.

Example [V Q-Octadecenyl isocyanate. Phosgene was passed into 450 parts of toluene for 15 minutes when 107 parts of 9-octadecenylamine was added with stirring. The mixture was heated to boiling and phosgene was passed through until no more hydrogen chloride was given off. After removal of the toluene, 91 parts of 9-octadecenyl isocyanate distilled at 181-1835" C. at 4 mm.

- Example V Cetyl and octadecyl isocyanates.-To a stirred solution of 390 parts of phosgene in 1300 parts of toluene was added a solution of 380 parts of mixed cetyland octadecylamines in 2500 parts of toluene. The mixture was heated to boiling and a slow stream of phosgene was passed through until hydrogen chloride was no longer evolved. The toluene was removed and 280 parts of mixed cetyl and octadecyl isocyanates distilled at 181-193 C. at 8 mm.

Example VI residue was obtained parts of decamethylene diisocyanate boiling at-154-15'7" C. at 4.5 'mm.

Any solvent which dissolves the amine and its hydrohalide, does not react with the amine, isocyanate, phosgene, or hydrogen chloride,, and

has a boiling point above the decomposition temperature of the intermediate carbamyl chloride, 1. e., above about 75 6., is operable. Suitable solvents include aromatic hydrocarbons, such as benzene, toluene, and xylene; aliphatic and alicyclic hydrocarbons, such as cyclohexane and kerosene; and halogenated hydrocarbons such as chlorobenzene, carbon tetrachloride, tetrachloroethylene, trichloroethylene, and tetrachioroethane. These and similar solvents may be substituted for the toluene of the examples.

The reaction is ordinarily carriedout at atmospheric pressure but operation at lower pressures is feasible'when using high boiling reactants and a high boiling solvent and facilitate removal of hydrogen chloride.

The process is generically applicable to any amine or mixture of amines of the formula R(NH:)= where R is an acyclic hydrocarbon radical having a chain of at least six carbon atoms and having a valence of :c or any hydrohalide thereof. Straight or branched chain saturated or unsaturated amines may be used, and the amino group or groups can be attached to a secondary or tertiary carbon atom as well as to a primary carbon atom.

Specific amines that are suitable include the 1 following: cetylamine, n-octylamine, z-ethylhexylamine, n-decylamine, 2-aminotridecane, 8-aminopentadecane, 2 aminoheptane, 2 amino-5- ethylnonane, hexamethylenediamine, octamethylenediamine, undecamethylenediamine, octadecamethylenediamine, z-methylhexamethylenediamine, 1,10-dimethyldecamethylenediamine, 2- tertbutylhexamethylenediamine, and the mixture of amines obtained by converting fatty oils to nitriles and hydrogenating these materials to amines. Oils that may be used for the production or mixed amines are coconut oil, lard oil. cottonseed oil, and sperm 011. These amines may be used as such, or may first be converted to the hydrochloride, -bromide, or -iodide.

The temperature used in the operation must be high enough to cause decomposition of the intermediate carbamyl chloride into the isocyanate and hydrogen chloride without causing the isocyanate to distill. Temperatures from 75 C. to 250 C. may be used but for convenience and economy, temperatures or IOU-200 C. are preferred. Refiuxing the solvent or passing an inert gas through the hot reaction mixture iaciliq tates removal of the hydrogen chloride.

Certain of the isocyanates which may be prepared by the process of the present invention are new and particularly useful. Among these are preferred the diisocyanates R-(NCO) 2, wherein R is a divalent acyclic hydrocarbon radical having a chain 01 at least six carbon atoms between the isocyanate groups.

The isocyanates prepared by the process of the present invention are oi. use as waterproofing agents, particularly for textiles.

The above description and examples are intended to be illustrative only. Any modification of or variation therefrom which conforms to the spirit of the invention is intended to be included within the scope of the claim.

I claim:

Decamethylene diisocyanate having a boiling point 01' 154-157 C. at 4.5 mm.

WILLIAM EDWARD HANFORD. 

